I'm not sure if you're serious, but there are a few problems with that.
First, there's a lot of crime that goes along with running a cartel. Selling marijuana may be legalized, but most of the cartel people have long criminal histories that aren't going away. Murder, torture, bribery, kidnapping and all that are still crimes.
Second, a good deal of a drug cartel's infrastructure is devoted to violence and smuggling. Obviously violence can't be part of a legitimate business. And unless they're trying to evade taxes, the smuggling stuff is just overhead compared to other shipping methods.
First, there's a lot of crime that goes along with running a cartel. Selling marijuana may be legalized, but most of the cartel people have long criminal histories that aren't going away. Murder, torture, bribery, kidnapping and all that are still crimes.
Second, a good deal of a drug cartel's infrastructure is devoted to violence and smuggling. Obviously violence can't be part of a legitimate business. And unless they're trying to evade taxes, the smuggling stuff is just overhead compared to other shipping methods.